Automatic time-controlled alarm system

ABSTRACT

In an electronically-timed multiple-alarm warning system, a plurality of sensors connected to a first switch which controls a first alarm, a first timing circuit triggered by the first switch and which operates a second switch after a first predetermined time delay, the second switch controlling a second alarm and a second alarm driving circuit, a second timing circuit for deenergizing the system after a second predetermined time delay, and a re-set switch for manually re-setting the system in case of false alarm.

Unite Sullivan States atent [54] AUTOMATIC TIME-CONTROLLED ALARM SYSTEM[73] Assignee: Standard-Farrington Alarm &

Signal Corp., Trevose, Pa.

22 Filed: May 8,1970

21 App1.No.: 35,684

[52] US. Cl ..340/213 R, 340/276, 340/277, 340/309.4, 340/328, 340/329,340/384 E,

[51] Int. Cl. ..G08b 29/00 [58] Field of Search.....340/2l3, 309.1,309.4, 309.5, 340/276, 277, 331, 328, 329, 393, 404, 213

[451 Aug. 29, 1972' 3,458,772 7/1969 Egart et a1. ..307/315 X 3,158,85011/1964 Poznanski ..340/261 X 1,685,329 9/1928 Lynch ..340/277 1,924,7838/ 1933 Goss ..340/277 3,393,361 7/1968 Martin ..340/309.4 3,162,77212/1964 Smith ..340/276 UX 3,204,146 8/ 1965 Kratochvil ..340/331 X3,319,247 5/1967 Zajanc ..340/404 Primary Examiner-David L. TraftonAttorney-Paul 81. Paul [57] ABSTRACT In an electronically-timedmultiple-alarm warning system, a plurality of sensors connected to afirst switch which controls a first alarm, a first timing circuittriggered by the first switch and which operates a R; 307/315 secondswitch after a first predetermined time delay, the second switchcontrolling a second alarm and a [56] References Clted second alarmdriving circuit, a second timing circuit UNITED STATES PATENTS forde-energizing the system after a second predetermined time delay, and are-set switch for manually re- 1,398,593 11/1921 Hopkins ..340/227setting the System in case of false alarm. 3,537,105 10/1970 Tellerman..340/213 X 3,550,111 12/1970 Ervin ..340/213 X 7 Claims, 2 DrawingFigures 17 SWITCHING 25 sac 0ND CIRCUTRY DELAY j OSCILLATOR DRIVER l 3MINUTE DELAY PHONE PATENTEDmszs I972 SHEET 2 [IF 2 INVENTORS. Joseph T.Sullivan BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention lies in the field of electronic alarm systems and, moreparticularly, self-powered electronic alarm systems with a re-setmechanism for terminating the alarm within a timed period.

2. Description of the Prior Art The need for effective alarm systems forprotection of person and property is a very critical need in the nationtoday. The rising rate of crimes committed against commercial andpersonal property has produced a soaring demand for efficient andeconomical alarm systems. A number of alarm systems are presentlyavailable commercially but generally are very expensive, unreliable, andmost critically, are given to producing false alarms. The high rate offalse alarms is a natural consequence of the conventional sensingmechanisms which are employed in such systems, e.g., pressure sensitivemats concealed beneath rugs and hidden door switches. To be effective,such sensors are normally placed in positions where they areinadvertently tripped by normal users of the property. Where such alarmsystems are connected to remote points by telephone, the false alarmsare automatically registered, as at a police station, with no effectivemeans for invalidating the false alarm. The police forces of many largecities are reporting an extremely high percentage of false alarms comingfrom such business and home alarm systems, causing expensive and highlytime consuming investigations by the police. There thus exists a greatneed for an efiicient alarm system which permits the use of conventionalsensing devices in the manner adapted to the particular property beingprotected, but which provides the user the ability to correct and cancelfalse sensor energizations of the system before false alarms aregenerated and transmitted.

SUMMARY OF THE INVENTION It is an object of this invention to provide aninexpensive, reliable and self-energized alarm system having a firstalarm triggered immediately upon operation of a sensor, and a secondalarm which is energized a given time delay thereafter, with means forde-energizing the alarm system during the time delay if the alarm isfalse, the second alarm acting as the true alarm.

Accordingly, a battery powered alarm system is provided having a firsthigh frequency relatively low volume alarm energized immediately upontripping of any one of a set of conventional sensors,, the highfrequency alarm being of a volume to alert anyone present that the alarmhas been tripped, but not being loud enough to provide warning, and notbeing remotely connected, as through a telephone line to a policestation. If the system is not de-energized within a given time periodpredetermined by a time delay circuit, a second true" alarm is energizedwhich may provide a warning signal in the area of the protectedproperty, and/or be remotely connected to a receiving station. A secondtime delay circuit turns off and resets the system after a secondpredetermined time period. The electrical portion of the system isbattery operated, the alarms being powered by cylinders of freon whichare solenoid-controlled.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow diagram showing thesignals which activate and deactivate the two alarms of the system.

FIG. 2 is a schematic diagram of the switching and timing circuitry ofthis invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT sensors are conventional sensingmechanisms used for the detection of intruders, fire, freezingtemperatures, etc., comprising thin pressure sensitive mats concealedbeneath rugs, hidden door and window switches, thermal sensitive andoptically sensitive devices. Also, conventional push-button, or panicbutton sensors may be utilized. When a sensor 11 is activated, a signalis transmitted to switching circuitry of control box 26, the switchingcircuitry including a switch which immediately switches on to provide anactivating signal which is coupled to the first alarm, designated 13.The switching circuitry also initiates a count of approximately 25seconds by counter 15. At the end of the 25 second time period, a signalis transmitted to oscillatordriver unit 16 which energizes alarm 17,causing that alarm to be driven repetitively, producing a pulsating highvolume sound. At the end of the 25 second time delay, delay circuit 15also transmits a signal to a second delay circuit 20 which counts a timedelay of approximately three minutes, after which a signal istransmitted back to the set-reset circuit 12 to turn off both alarms 13and 17 and reset the system for the next sensor signal.

Referring now to FIG. 2, the details of the electronic control circuitryare seen in more detail. A DC power supply 10 is connected to terminals29 and 30. The supply may be a conventional 12 volt battery. THe

positive terminal is connected through a resistor 31,

from lightening flashes, from tripping SCR 38.

The anode of SCR 38 is coupled through normally closed switch 92 to thepositive terminal 30, and the cathode is coupled to the negativeterminal through resistor 40 in parallel with a series combination ofresistor 41 and capacitor 42. Resistor 40 is typically 10 K ohms,resistor 41 is typically 1 megohm and capacitor 42 is typically 10microfarads. Resistor 41 in combination with capacitor 42 provides atime constant of about 10 seconds.

From the above, it is seen that whenever a sensor 11 is tripped, causinga short circuit between terminals 32 and 33, a plus voltage is appliedto the gate of SCR 38, causing it to conduct. SCR 38 will have a smallbut negligible voltage drop across it, such that the cathode will be atappreciably plus 12 volts with respect to negative terminal 30. Thecathode is tied directly to terminal 45, and terminal 46 is tieddirectly to negative terminal 30, such that an appreciably full 12 voltsignal appears across terminals 45 and 46, which in turn are coupled tofirst alarm mechanism 13. Accordingly, as soon as a sensor 11 istripped, power is supplied to alarm 13.

As was mentioned before, the combination of resistor 41 and capacitor 42may typically have a time constant of seconds. The junction 43 betweenthe resistor and capacitor is tied to the emitter of unijunctiontransistor 50, which has one base terminal tied to the cathode of SCR 38and the other to resistor 51 and capacitor 52. The unijunctiontransistor 50 is turned on when capacitor 42 charges to approximately 75percent of the supply voltage. The output of the unijunction transistoris derived across resistor 51 in parallel with capacitor 52, typically10 microfarads, and is transmitted through a resistor 53 to a second SCR55. As capacitor 52 charges up, the voltage supplied to the gate of SCR55 reaches a value sufficient to turn it on, providing a closed pathfrom positive terminal 29 through SCR 55 and resistor 56 to the negativeterminal. Resistor 56, connected to the cathode of SCR 55, is a currentlimiting resistor, chosen low enough that current is maintained throughSCR 55. The combination of the time for charging resistor-capacitorcombination 41-42 and for charging capacitor 52 through unijunctiontransistor 50 is typically 25 seconds and, of course, may be varied byvarying the parameters of components 41, 42 and 52.

Thus, after approximately a 25 second time delay, a signal ofapproximately +12 volts, neglecting the voltage drop across SCR 55,appears on the cathode terminal of SCR 55, which is connected to thepositive solenoid terminal 58. Solenoid 60, which actuates second alarm17, is tied between positive terminal 58 and negative terminal 59,having thereacross an arc suppression diode 62.

Still referring to FIG. 2, the portion designated 16 comprises theadjustable oscillator-driver, for periodically energizing solenoid 60,which in turn causes alarm mechanism 17 to be driven. Terminal 59 isconnected to a variable resistor, or pot, 65, typically of 25 kilohms,the other terminal of which is connected to a parallel combination ofresistor 66 and diode 67. Resistor 66 is typically 47 kilohms in value,and in turn is connected at node 68 to a capacitor 69 and a second 25kilohm pot 70. The other terminal of capacitor 69 is connected tonegative terminal 30, and the other terminal of pot 70 is connected tothe base of transistor 75. The emitter of transistor 75 is alsoconnected to negative terminal 30, and the collector is connected to thecoil 76 of a reed relay having make-break contacts 77 connected betweenterminals 59 and 30.

In operation, capacitor 69, typically 500 microfarads, charges throughpot 65 and resistor 66. When capacitor 69 charges sufficiently, apositive voltage is transmitted through pot 70 to the base of transistor75, turning the transistor on, thereby driving current through relaycoil 76, causing switch 77 to close. During the time that capacitor 69is charging, the charging current, which flows through solenoid 60, isinsufficient to operate the solenoid. However, when switch 77 is closed,appreciably the full 12 volt supply is placed across solenoid 60,causing it to operate and activate alarm mechanism 17.

However, when switch 77 closes, capacitor 69 discharges through diode 67and pot 65. Pot 65 may be adjusted so as to determine the dischargetime. In a similar manner, pot may be adjusted so as to determine thevoltage to which capacitor 69 must be charged before transistor isturned on, thereby activating relay 77. When capacitor 69 dischargessuffciently, the positive bias on transistor 75 is reduced such that thetransistor turns off, at which time current ceases to flow through relaycoil 76 and relay 77 is opened, terminating the energization of solenoid60. Thus, the circuit provides for periodic energization andde-energization of solenoid 60, with means to control the on-off periodsby adjusting pots 65 and 70.

The dashed line marked 20 indicates a second time delay circuit which,in the preferred embodiment of this invention, times a delay ofapproximately three minutes. The cathode of SCR 55, which carries apositive signal after the first time delay, is tied to a resistor 81,the other terminal of which is tied at node 82 to capacitor 83. Resistor81 and capacitor 83 are chosen to have a time constant in excess of 1minute, e.g., 22 megohms and 4 microfarads respectively. Node 82 isconnected to the base of transistor 84, the emitter of which is coupledinto the base of transistor 85 in a conventional Darlington-typecircuit. The emitter of transistor 85 is coupled to a capacitor 86,being typically 500 microfarads, which capacitor is charged through theDarlington circuit when the voltage at 82 rises to a level sufficient toturn on transistor 84. The emitter of transistor 85 is connected to theemitter of unijunction transistor 89, such that the voltage acrosscapacitor 86 turns on unijunction transistor 89 when it rises to asufficient level. Transistor 89 is in series with a resistor 90 andrelay coil 91, between the cathode of SCR 55 and negative terminal 30.Thus, when transistor 89 is turned on, current flows through relay coil91, opening relay switch 92, thereby cutting off current to SCRs 38 and55, and thereby de-energizing the entire circuit. Upon de-energizationof the circuit, current ceases to flow through coil 91, at which pointswitch 92 is again closed, and the circuit is reset to be tripped againby activation of a sensor 1 1.

Reviewing the timing of the circuit, energization of the circuit isinitiated by the tripping at a given time, T of a sensor 11. The firstalarm 13 is immediately energized at such time T At a later time, Tequal to T plus about 25 seconds, the second alarm '17 is energized. Ata time T equal to T plus about 3 minutes, both alarms are de-energizedand the system is reset to be triggered again by one of the sensors.

it is frequently desired to connect an automatic alarm system, such asthe system of this invention, to a telephone for automatic dialing toprovide a remote signal, as at a police station. This can be done simplyand reliably by energizing a relay coil, which relay activates aconventional automatic dialing mechanism. In the system of thisinvention, the desired remote signaling may be achieved after theinitial 25 second delay by placing a telephone relay coil 95 between thecathode of SCR 55 and negative terminal 30. The remote telephone signalmay be in place of or in addition to energization of alarm mechanism 17.

in operation, if the alarm has been falsely tripped, there is a timeperiod of about 25 seconds during which the property owner may reset thealarm, avoiding energization of the louder alarm 17 or transmission of aremote signal to a police station. Of course, this time period may beset to any desired length for the particular user. By depressingbutton-switch 99, connected between battery and terminal 29, the circuitis denergized and reset. The user may install button switch 99 at anyconveniently secret location in his home or on the property beingprotected.

It is to be noted that the system of this invention is entirelyself-powered. The electrical system is operated by battery 10, whichbattery is not drained at all except when the system is activated bytripping of a sensor. This is because both SCRs 38 and 55 are normallyopen, and as long as they are open, no current can be conductedtherethrough to the remainder of the circuit. Alarm 13 is typically aconventional small mechanical oscillator which produces a highfrequency, extremely irritating sound. lt is designed to give sufficientalert to the user in case of false alarm, but is not powerful enough toalert people outside of the property. A typical such high frequency unitdraws from 6 to 16 milliamps of power. The second alarm mechanism 17 istypically a freon powered, solenoid actuated horn, which produces anextremely loud and strident noise. The freon is stored in a cylinder,and is released upon activation of the solenoid, which drawsapproximately three quarters of an ampere when energized. The cylindermay be placed at any convenient location, and connected through tubingto the horn which is mounted at a suitable location. It is noted thatmore than one such horn may be powered by the control system of thisinvention.

The novelty of this invention lies in the control devices, circuitry andcomponents as detailed above, and is not limited to any particularapplication. For instance, the invention may be suitably used in homes,commercial properties, on boats, and in a wide variety of applications.it may be used for the detection of fire by utilizing a temperaturesensitive sensor 11. Similarly, it may be utilized to sense freezingconditions, such as by immersing a sensor 11 in a liquid which is to bemonitored so as to prevent it from freezing lclaim:

l. A self powered alarm system which provides for a predetermined timeperiod during which a false alarm may be corrected, comprising:

a. electrical sensor means for sensing an alarm condition;

b. electrically actuated first alarm signal means for generating a firstaudible alarm signal;

c. first electronic alarm switching means switchably connecting saidsensor means and said first alarm signal means for energizing said firstalarm signal means immediately upon tripping of said sensor means;

d. first electronic time delay means, connected to and triggered by saidfirst alarm switching means, for measuring a first time delay followingenergization of said first alarm signal means;

e. electrically actuated second alarm signal means for producing asecond alarm signal;

f. second alarm signal interrupt means for periodi- 6 pally ipterruptiigsaid econd alarm silg nal meana or driving sai secon alarm signal eans,an having a transistor with its input in parallel with a capacitor andits output connected to a relay, the transistor and relay cooperating tocause the capacitor to alternately charge and discharge, producing analternating signal which drives said second alarm signal means, saidsecond alarm signal interrupt means being connected in series with saidsecond alarm signal means so that electrical current through said secondalarm signal means operates said second alarm signal interrupt means;

g. second electronic time delay means for measuring a second time delay,said second time delay commencing at the termination of said first timedelay;

h. automatic reset means connected to and driven by said second timedelay means for de-energizing and re-setting said alarm system;

i. false alarm reset means for manually de-energizing and resetting saidalarm system;

j. power means for energizing said alarm system; and

k. second electronic alarm switching means, connected to and activatedby said first time delay means, for connecting said power means to saidsecond alarm signal means and to said second time delay means when saidfirst time delay has been measured.

2. The system as described in claim 1 wherein said second alarm signalmeans comprises a freon energized horn, said horn being solenoidcontrolled, said first alarm signal means comprising a high frequencyrelatively low volume horn, and said power means comprising a batteryhaving normally negligible power drain unless said sensing means istripped.

3. The system as described in claim 1 wherein said first time delaymeans comprises a resistor-capacitor combination which drives aunijunction transistor, the output of said unijunction transistor beingcoupled to a parallel combination of resistance and capacitance.

4. The system as described in claim 1 wherein said second time delaymeans comprises a resistor and capacitor in combination driving aDarlington-type amplifier having a capacitor connected across the outputthereof.

i 5. The system as described in claim 4 wherein said Darlington-typeamplifier is connected to the input of a transistor switch, said inputhaving a capacitor connected to same, and wherein said automatic resetmeans comprises a reed relay having a relay coil connected to the outputof said transistor switch and which, when energized, disconnects saidpower means from the remainder of said system.

6. The system as described in claim 1 wherein said I alarm signaldriving means comprises first and second variable resistances forcontrolling the frequency of driving said alarm signal means.

7. The systemas described in claim 1 wherein said first and secondelectronic alarm switching means are connected to said power means in amanner that all current from said power means passes through one or theother of said switching means, such that there is power output deliveredfrom said power means only when said sensor means senses an alarmcondition.

1. A self powered alarm system which provides for a predetermined timeperiod during which a false alarm may be corrected, comprising: a.electrical sensor means for sensing an alarm condition; b. electricallyactuated first alarm signal means for generating a first audible alarmsignal; c. first electronic alarm switching means switchably connectingsaid sensor means and said first alarm signal means for energizing saidfirst alarm signal means immediately upon tripping of said sensor means;d. first electronic time delay means, connected to and triggered by saidfirst alarm switching means, for measuring a first time delay followingenergization of said first alarm signal means; e. electrically actuatedsecond alarm signal means for producing a second alarm signal; f. secondalarm signal interrupt means for periodically interrupting said secondalarm signal means for driving said second alarm signal means, andhaving a transistor with its input in parallel with a capacitor and itsoutput connected to a relay, the transistor and relay cooperating tocause the capacitor to alternately charge and discharge, producing analternating signal which drives said second alarm signal means, saidsecond alarm signal interrupt means being connected in series with saidsecond alarm signal means so that electrical current through said secondalarm signal means operates said second alarm signal interrupt means; g.second electronic time delay means for measuring a second time delay,said second time delay commencing at the termination of said first timedelay; h. automatic reset means connected to and driven by said secondtime delay means for de-energizing and re-setting said alarm system; i.false alarm reset means for manually de-energizing and resetting saidalarm system; j. power means for energizing said alarm system; and k.second electronic alarm switching means, connected to and activated bysaid first time delay means, for connecting said power means to saidsecond alarm signal means and to said second time delay means when saidfirst time delay has been measured.
 2. The system as described in claim1 wherein said second alarm signal means comprises a freon energizedhorn, said horn being solenoid controlled, said first alarm signal meanscomprising a high frequency relatively low volume horn, and said powermeans comprising a battery having normally negligible power drain unlesssaid sensing means is tripped.
 3. The system as described in claim 1wherein said first time delay means comprises a resistor-capacitorcombination which drives a unijunction transistor, the output of saidunijunction transistor being coupled to a parallel combination ofresistance and capacitance.
 4. The system as described in claim 1wherein said second time delay means comprises a resistor and capacitorin combination driving a Darlington-type amplifier having a capacitorconnected across the output thereof.
 5. The system as described in claim4 wherein said Darlington-type amplifier is connected to the input of atransistor switch, said input having a capacitor connected to same, andwherein said automatic reset means comprises a reed relay having a relaycoil connected to the output of said transistor switch and which, whenenergized, disconnects said power means from the remainder of saidsystem.
 6. The system as described in claim 1 wherein said alarm signaldriving means comprises first and second variable resistances forcontrolling the frequency of driving said alarm signal means.
 7. Thesystem as described in claim 1 wherein said first and second electronicalarm switching means are connected to said power means in a manner thatall current from said power means passes through one or the other ofsaid switching means, such that there is power output delivered fromsaid power means only when said sensor means senses an alarm condition.